Reply Obj. 2:  Mortal sin is incompatible with divinely infused virtue, especially if this be considered in its perfect state.  But actual sin, even mortal, is compatible with humanly acquired virtue; because the use of a habit in us is subject to our will, as stated above (Q. 49, A. 3):  and one sinful act does not destroy a habit of acquired virtue, since it is not an act but a habit, that is directly contrary to a habit.  Wherefore, though man cannot avoid mortal sin without grace, so as never to sin mortally, yet he is not hindered from acquiring a habit of virtue, whereby he may abstain from evil in the majority of cases, and chiefly in matters most opposed to reason.  There are also certain mortal sins which man can nowise avoid without grace, those, namely, which are directly opposed to the theological virtues, which are in us through the gift of grace.  This, however, will be more fully explained later (Q. 109, A. 4).

Reply Obj. 3:  As stated above (A. 1; Q. 51, A. 1), certain seeds or principles of acquired virtue pre-exist in us by nature.  These principles are more excellent than the virtues acquired through them:  thus the understanding of speculative principles is more excellent than the science of conclusions, and the natural rectitude of the reason is more excellent than the rectification of the appetite which results through the appetite partaking of reason, which rectification belongs to moral virtue.  Accordingly human acts, in so far as they proceed from higher principles, can cause acquired human virtues. ________________________

THIRD ARTICLE [I-II, Q. 63, Art. 3]

Whether Any Moral Virtues Are in Us by Infusion?

Objection 1:  It would seem that no virtues besides the theological virtues are infused in us by God.  Because God does not do by Himself, save perhaps sometimes miraculously, those things that can be done by second causes; for, as Dionysius says (Coel.  Hier. iv), “it is God’s rule to bring about extremes through the mean.”  Now intellectual and moral virtues can be caused in us by our acts, as stated above (A. 2).  Therefore it is not reasonable that they should be caused in us by infusion.

Obj. 2:  Further, much less superfluity is found in God’s works than in the works of nature.  Now the theological virtues suffice to direct us to supernatural good.  Therefore there are no other supernatural virtues needing to be caused in us by God.

Obj. 3:  Further, nature does not employ two means where one suffices:  much less does God.  But God sowed the seeds of virtue in our souls, according to a gloss on Heb. 1 [Cf.  Jerome on Gal. 1:  15, 16].  Therefore it is unfitting for Him to cause in us other virtues by means of infusion.

On the contrary, It is written (Wis. 8:7):  “She teacheth temperance and prudence and justice and fortitude.”